The infectivity of chicken pox lasts for -

Chicken pox Causative agent → Varicella zoster virus (Herpes simplex type III). Portal of entry → Respiratory tract or conjunctiva I. P. → 10-21 days. Infectious period → 2 days before and 5 days after the onset of rash. Secondary attack rate is high → 90 % Age group → 5-9 Yrs. C/Fs - has two stages 1. Pre-eruptive stage fever, back pain, malaise, shivering 2.Eruptive stage Rash is symmetrical, mostly on flexor surface. Centripetal in distribution Mainly On trunk, less common on arms and leg Palms and soles are not usually affected There is rapid evolution of rash Rash is plemorphic, that is, all stages of rash (Papule, vesicle and crusts) may be seen simultaneously. Disease is more severe in adults than in children.